Ascites: aetiology, mortality and the prevalence of spontaneous bacterial peritonitis

Abstract

Objective: To assess the aetiology, prognosis and prevalence of spontaneous bacterial peritonitis (SBP) in patients hospitalized for ascites. The validity of an elevated (>11 g/l) serum-ascites albumin gradient (SAAG) in the diagnostic work-up was evaluated. Mortality trends were observed over two periods of time.

Material and methods: A total of 231 consecutive patients who underwent diagnostic paracentesis between February 1994 and December 1998 and January 2005 and March 2007 were included in the study. The definition of SBP comprised polymorphonuclear cell count >250/mm(3) without evidence of other intra-abdominal source of infection. SAAG was obtained and the Child-Pugh classification applied. Survival rates were obtained from medical records.

Results: The most common causes of ascites were alcohol liver cirrhosis (n=143; 62%), malignancy (n=30; 13%), non-alcoholic cirrhosis (n=11; 5%) and malignancy with cirrhosis (n=11; 5%). The prevalence of SBP in cirrhosis was 6.7% (95% CI 2.8-10.5%). Overall mortality rates at 1 month, 6 months and 1 year were 22%, 40% and 48%, respectively, and remained unchanged between the intervals. Patients with grade C liver disease had higher 1-month (26% versus 6%), and 6-month (44% versus 27%) mortality rates than grade B patients, but commensurate 1-year mortality (49% versus 47%). SAAG was >or=11 g/l in 85% of patients with obvious portal hypertension and in 30% with malignancy, ascites albumin level <or=9 g/l in 69% and 20%, respectively.

Conclusions: Mortality in patients with ascites was high. The occurrence of SBP was relatively low in our series, with a high proportion of alcoholic cirrhosis. SAAG was inaccurate in differentiating ascites caused by portal hypertension or malignancy.